Thursday, March 01, 2007

Cracked windshields at DIA caused by very fine FOD?

Denver International AirportRemember the mysterious event last month when the windshields of more than a dozen aircraft cracked on the same stormy day in Denver? At the time, airport officials said that the cause was "baffling." Now an article in the Denver Post says that 'fine particles' cracked those windshields.

The damaged aircraft belonged to SkyWest, Frontier, and Great Lakes airlines. Six of the planes developed cracks in their windshields during takeoff. One windshield cracked after landing, and two more happened during taxi. Three parked aircraft sustained windshield cracks as well, and one windshield cracked during pushback. One aircraft developed the problem in flight, at 19,000 feet.

It was cold, snowy, and very windy that day. Winds were gusting up to 48mph during the three-hour period when the windshields cracked. NTSB investigator Jennifer Kaiser said that "The only commonality across aircraft type, operator, location, time and phase of flight was the wind and weather."

The Denver Post says:
Cracked windshields on 14 planes at Denver International Airport were caused by "foreign object debris," air safety investigators said Tuesday.

Microscopic analysis of the 21 front and side windshields cracked during a storm revealed fine particles causing pitting that in turn caused cracking, National Transportation Safety Board investigator Jennifer Kaiser said. Only the outer layer of the triple-layer windshields cracked and none of the planes declared emergencies.
Flying sand? Ice pellets? We still don't know. The exact nature of the debris was unable to be determined by investigators.